EP0362400A1 - Methode de cuisson d'une structure ceramique a nid d'abeilles - Google Patents

Methode de cuisson d'une structure ceramique a nid d'abeilles Download PDF

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Publication number
EP0362400A1
EP0362400A1 EP19890902816 EP89902816A EP0362400A1 EP 0362400 A1 EP0362400 A1 EP 0362400A1 EP 19890902816 EP19890902816 EP 19890902816 EP 89902816 A EP89902816 A EP 89902816A EP 0362400 A1 EP0362400 A1 EP 0362400A1
Authority
EP
European Patent Office
Prior art keywords
temperature
firing
honeycomb structure
outside
pore
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19890902816
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German (de)
English (en)
Other versions
EP0362400A4 (en
EP0362400B1 (fr
Inventor
Kazuhiro 201 Minami-Kazoku Apart. Miyahara
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NGK Insulators Ltd
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NGK Insulators Ltd
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Publication date
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Publication of EP0362400A1 publication Critical patent/EP0362400A1/fr
Publication of EP0362400A4 publication Critical patent/EP0362400A4/en
Application granted granted Critical
Publication of EP0362400B1 publication Critical patent/EP0362400B1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B01D39/2068—Other inorganic materials, e.g. ceramics
    • B01D39/2072—Other inorganic materials, e.g. ceramics the material being particulate or granular
    • B01D39/2075—Other inorganic materials, e.g. ceramics the material being particulate or granular sintered or bonded by inorganic agents
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/64—Burning or sintering processes
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/0006—Honeycomb structures

Definitions

  • This invention relates to a method which is suitable for firing a ceramic honeycomb structure.
  • a ceramic product of honeycomb shape, or a ceramic honeycomb structure has been made by preparing a ceramic green body through mixing of ceramic materials with a molding aids and a pore-forming agent, molding the body into a honeycomb-shaped ceramic green body through extrusion of the mixed body, and finally firing the honeycomb-shaped ceramic green body in a firing furnace at a predetermined temperature.
  • the molding aids to be mixed with the ceramic materials for the above firing of the honeycomb structure is for instance an organic binder, such as methyl cellulose, carboxymethylcellulose, polyvinyl alcohol, starch paste, flour, glycerin, and the like or a surface active agent, or wax, etc.
  • the above pore-forming agent to be used with the ceramic materials is for instance graphite, saw dust, starch etc.
  • Such molding aids and pore-forming agent have the following special properties; namely, the molding aids or pore-forming agent is hard to heat from the outside of the honeycomb structure, but once ignited, it burns rapidly and generates heat (the igniting temperature varies depending on the kind of auxiliary).
  • the rapid burning of the molding aids or pore-forming agent results in uneven temperature distribution in the structure and tends to cause cracks within or at end portions of the final ceramic honeycomb structure.
  • the oxygen concentration in the firing atmosphere at a temperature in ignition ranges of the molding aids or pore-forming agent varies depending on fluctuation of the weight of ceramic green body loaded in the furnace (to be referred to as "the loaded weight", hereinafter).
  • the manner in which the molding aids or pore-forming agent within the ceramic honeycomb body burns varies, so that the temperature difference between the inside and outer portions of the ceramic honeycomb body becomes large or small. In consequence, sometimes cracks generate but sometimes not, resulting in a problem that the quality of the product is not uniform and stable production is hard to realize.
  • the pore-forming agent comes in contact with oxygen of the firing atmosphere and burns out in a certain time period, so as to produce fine holes of desired diameter. It has been a practice to terminate the firing process with a certain time relationship with the timing of the burn out of the pore-forming agent.
  • the oxygen concentration in the firing atmosphere varies and the kind of the pore-forming agent varies, so that the burning characteristics of the pore-forming agent changes.
  • pore-forming agent within the ceramic honeycomb body sometimes burn out but sometimes not, and there is a problem that stable production of fired goods with uniform distribution of fine hole diameter throughout the inside and outer portions thereof is difficult to attain.
  • an object of the present invention is to solve the above-mentioned problems of the prior art by providing an improved method of firing ceramic honeycomb structure which ensures stable production of high-quality product.
  • the invention is to provide a method of firing a ceramic honeycomb structure at a predetermined temperature in a predetermined atmosphere, characterized in that temperatures at inside and outside of the ceramic honeycomb structure are detected by a temperature sensing means, and combustion of burner means is controlled based on the temperatures thus detected.
  • the temperatures at the inside and outside of the ceramic honeycomb structure are detected, and based on the detected temperatures, the outside temperature is controlled relative to the inside temperature by regulating the combustion of a burner means which heats the ceramic honeycomb structure from the outside thereof.
  • a burner means which heats the ceramic honeycomb structure from the outside thereof.
  • the heat supply from the burner means will be increased so as to raise the outside temperature to a level corresponding to the inside temperature.
  • the heat supply from the burner means will be decreased so as to suppress the outside temperature.
  • the outside temperature of the body being fired coincides with the inside temperature thereof.
  • the combustion of a burner means is controlled while detecting and monitoring the inside and outside temperatures until the above temperature coincidence is reached, for instance by keeping constant combustion in the vicinity of the above coincidence. With such control, stable firing can be effected even when the burning characteristics of the pore-forming agent varies due to fluctuation in the loaded weight of shaped bodies or due to change in the state of the pore-forming agent, and such stable firing enables production of high-quality goods.
  • a shaped body Before firing a ceramic honeycomb structure by the method of the invention, a shaped body is prepared at first by mixing ceramic materials of desired grain size, making a plastic batch by adding a molding aids and/or a pore-forming agent in the mixture so as to plasticize the mixture, molding the plastic batch into a shaped body of honeycomb form through extrusion, and then drying the extruded body.
  • a desired ceramic honeycomb structure can be obtained by firing the above shaped body by the method of the invention; namely, by firing the shaped body, while detecting the temperatures at the inside and outside of the shaped body, so as to control the combustion of a burner means, which heats the ceramic honeycomb structure from the outside thereof, in such a manner that the outside temperature of the shaped body is regulated to a level corresponding to the inside temperature thereof.
  • thermocouples are applied to the specific shaped body, one inside and one outside thereof, so as to measure the temperature difference between the inside and outside.
  • the thermocouples measure the temperature difference between the inside and outside (inside-outside temperature difference) of the honeycomb structure.
  • the above inside-outside temperature difference is generally large due to heat generation from such burning aids unless it is fully burnt out.
  • Area having such inside-outside temperature difference is detected, and the combustion of a burner means is controlled at the detected area until the complete burn out of the pore-forming agent (coincidence of the inside temperature with the outside temperature) is reached.
  • the oxygen concentration in the firing atmosphere is kept on excess side, because it is hard for the pore-forming agent contained within the inside of the honeycomb shaped body to come in contact with oxygen of the firing atmosphere, and it is hard to ignite and to burn out such aids unless excess oxygen is available.
  • a suitable molding aids can be selected, depending on the use, from the group consisting of an organic binder, such as methyl cellulose, carboxymethylcellulose, polyvinyl alcohol, starch paste, flour, glycerin, and the like, a surface active agent, wax, etc.
  • a suitable pore-forming agent can be selected from the group consisting of graphite, saw dust, starch etc.
  • Shaped bodies 10 were prepared by weighing and mixing ceramic materials of kaolin and alumina to produce a mixture of mullite composition, plasticizing the mixture by adding methyl cellulose as a molding aids, molding the plasticized mixture, and drying. Separately, shaped bodies with flour added therein as a molding aids were also prepared.
  • the shaped bodies 10 were loaded in a firing furnace 11 by placing them on shelves 13 carried by a mobile truck 12 in the furnace.
  • the loading was effected at the loaded weights of Table 1 and the shaped bodies 10 were heated with a mean temperature rise rate of the same table.
  • the temperature was increased by combustion at burners 14 buried in opposite sidewalls of the furnace 11.
  • flame interrupting boards 16 were disposed between outside posts of the shelves 13, which interrupting boards 16 were solid members made of mullite-mixed body. Shelf boards 15 were placed at the bottom and top of the shelves 13.
  • Two thermocouples 17 were applied to one of the shaped bodies 10 placed in the firing furnace 11, one at the inside and one at the outside thereof.
  • the active portion of an oxygen sensor 18 was disposed within the firing furnace 11 and it was connected to the outside through the sidewall of the furnace.
  • the firing temperature was raised to a maximum temperature of 1,400°C and the maximum temperature was kept for 2.5 hours. Then, it was cooled at a rate of 150°C/hour.
  • Fig. 2a shows the temperature variation during the firing of the specimen 4, and one can note a temperature difference between the inside and the outside of the shaped body in a temperature range of 200-300°C due to the burning heat of the molding aids. Such temperature difference appears to be the cause of the cracks.
  • the combustion of the burners was controlled in response to the rise and fall of the body inside temperature, and the inside-outside temperature difference of the shaped body was minimized as shown in Fig. 2b, and no cracks were generated in the specimen 1.
  • Shaped bodies were prepared by mixing ceramic materials of talc, kaolin and alumina at a rate of cordierite composition, plasticizing the mixture through addition of starch paste as a molding aids and saw dust as a pore-forming agent, molding the plasticized mixture, and drying. Separately, shaped bodies with graphite added therein as a pore-forming agent were also prepared.
  • the shaped bodies were loaded in the shelves of the firing furnace 11 to fire them in the manner similar to that of Experiment 1 except the conditions of Table 2.
  • the temperature was raised to a maximum temperature of 1,350°C and the maximum temperature was kept for 6 hours. Then, it was cooled.
  • the result of the above firing is shown in Table 2.
  • Fig. 3a shows the temperature variation during the firing of the specimen 4, in which temperature differences between the inside and the outside of the shaped body are noted during temperature rise at two ranges of 200-300°C and 800-900°C, and such temperature differences appear to be the cause of the cracks.
  • the head quantity from the combustion at the burners was increased or decreased in response to the rise and fall of the body inside temperature, and the inside-outside temperature difference of the specimen 1 was minimized during the temperature rise as shown in Fig. 3b, and no cracks were generated in the specimen 1.
  • Shaped bodies were prepared by mixing ceramic materials of talc, kaolin and alumina at a rate of cordierite composition, plasticizing the mixture through addition of glycerin as a molding aids and graphite as a pore-forming agent, molding the plasticized mixture, and drying. Separately, shaped bodies with saw dust therein as a pore-forming agent were also prepared.
  • the shaped bodies were loaded in the shelves of the firing furnace 11 to fire them in the manner similar to that of Experiment 1 except the conditions of Table 3.
  • the temperature was raised to a maximum temperature of 1,410°C and the maximum temperature was kept for 10 hours. Then, it was cooled.
  • the result of the above firing is shown in Table 3.
  • the specimen 1 of the invention and specimen 4 of the prior art in this Experiment will be compared by referring to the data of Table 3.
  • combustion control in response to the shaped body temperature was not effected, and its firing was finished after having a temperature difference between the inside and the outside of the shaped body at a range of 200-320°C during the temperature rise as shown in Fig. 4a.
  • the heat quantity from the combustion at the burners was increased or decreased in response to the rise and fall of the body inside temperature, and the inside-outside temperature difference of the specimen 1 was minimized during the temperature rise as shown in Fig. 4b.
  • the combustion of the pore-forming agent in the above-mentioned temperature range of 800-900°C perfect combustion was confirmed by keeping the burner combustion conditions constant while maintaining a constant rate of temperature rise or constant slope of the temperature rise curve.
  • Rate of crack occurrence (%) was checked by visual inspection of the fired bodies after the above firing treatment. No cracks were found in the specimen of the invention.
  • the burning degree of the pore-forming agent there was no residual of incompletely burnt pore-forming agent and the inside-outside difference of fine hole diameter was within 1-2 ⁇ m in the case of the specimens of the invention.
  • heat quantity from burner means is increased or decreased in the temperature range for combustion of the molding aids or pore-forming agent, in response to the rise or fall of the inside temperature of the honeycomb body being fired, which inside temperature change is due to rapid combustion of such auxiliaries.
  • the temperature at the outer portion of the honeycomb body is controlled, i.e., raised or lowered, so as to eliminate the inside-outside temperature difference. For instance, constant burner conditions are maintained until complete burn out of the pore-forming agent is confirmed, so as to prevent the occurrence of any cracks within and at outer portions of the honeycomb structure.
  • the firing is effected in such a manner that the pore-forming agent is burnt uniformly throughout the honeycomb structure, from the inside to the outer portion thereof, so as to ensure stable production of high-quality fired products having fine holes whose diameters are uniform through inside and outer portions of the products.
  • the method of the invention is useful for firing ceramic honeycomb structure.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Structural Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtering Materials (AREA)
  • Furnace Details (AREA)

Abstract

Procédé de cuisson consistant à détecter les températures sur les côtés interne et externe d'une structure céramique à nid d'abeilles, à réguler la combustion d'un brûleur pour le chauffage depuis l'intérieur de la structure céramique à nid d'abeilles, afin de réguler la température de l'autre côté en tenant compte de la température interne prise comme référence en fonction de la température détectée, et à cuire la structure céramique à nid d'abeilles dans un seul four dans une atmosphère déterminée et à une température déterminée. La présente invention décrit un procédé de cuisson permettant de rendre uniforme la combustion d'un agent porogène à l'intérieur et à l'extérieur du produit, sans provoquer de fissures à l'intérieur et dans les extrémeités de la structure à nid d'abeille, et permettant de cuire de manière stable une structure à nid d'abeilles de grande qualité, dont les diamètres des pores ne présentent pas de différences entre l'intérieur et l'extérieur de la structure.
EP89902816A 1988-02-25 1989-02-23 Methode de cuisson d'une structure ceramique a nid d'abeilles Expired - Lifetime EP0362400B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP40599/88 1988-02-25
JP63040599A JPH01215765A (ja) 1988-02-25 1988-02-25 セラミックハニカム構造体の焼成法

Publications (3)

Publication Number Publication Date
EP0362400A1 true EP0362400A1 (fr) 1990-04-11
EP0362400A4 EP0362400A4 (en) 1991-09-25
EP0362400B1 EP0362400B1 (fr) 1993-02-24

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EP89902816A Expired - Lifetime EP0362400B1 (fr) 1988-02-25 1989-02-23 Methode de cuisson d'une structure ceramique a nid d'abeilles

Country Status (3)

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EP (1) EP0362400B1 (fr)
JP (1) JPH01215765A (fr)
WO (1) WO1989008087A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0549873A1 (fr) * 1992-01-03 1993-07-07 Corning Incorporated Procédé de fabrication de produits céramiques poreux à utiliser comme filtres de particules pour moteurs diesel
WO2006048003A1 (fr) * 2004-11-03 2006-05-11 Ctb Ceramic Technology Gmbh Procede et dispositif pour realiser la cuisson acceleree de pieces moulees ceramiques poreuses

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100554217C (zh) * 2004-07-14 2009-10-28 日本碍子株式会社 多孔质蜂窝结构体的制造方法
JP4532319B2 (ja) * 2005-03-28 2010-08-25 日本碍子株式会社 多孔質体の焼成方法及び装置
KR101360630B1 (ko) * 2005-08-23 2014-02-07 다우 글로벌 테크놀로지스 엘엘씨 세라믹 벌집체의 개선된 결합제 제거 방법
JP7022593B2 (ja) * 2018-01-15 2022-02-18 日本碍子株式会社 セラミックス焼成体の製造方法、及びセラミックス成形体の焼成方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0357789A1 (fr) * 1988-02-10 1990-03-14 Ngk Insulators, Ltd. Procede de production d'un corps ceramique d'une structure en nid d'abeille

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54138005A (en) * 1978-04-19 1979-10-26 Ngk Spark Plug Co Manufacture of honeycomb structure body made of gammaaal203

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0357789A1 (fr) * 1988-02-10 1990-03-14 Ngk Insulators, Ltd. Procede de production d'un corps ceramique d'une structure en nid d'abeille

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO8908087A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0549873A1 (fr) * 1992-01-03 1993-07-07 Corning Incorporated Procédé de fabrication de produits céramiques poreux à utiliser comme filtres de particules pour moteurs diesel
WO2006048003A1 (fr) * 2004-11-03 2006-05-11 Ctb Ceramic Technology Gmbh Procede et dispositif pour realiser la cuisson acceleree de pieces moulees ceramiques poreuses

Also Published As

Publication number Publication date
EP0362400A4 (en) 1991-09-25
JPH01215765A (ja) 1989-08-29
EP0362400B1 (fr) 1993-02-24
WO1989008087A1 (fr) 1989-09-08

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